Gear grinding machines are known in which a rolling cam, together with rolling drive means controls the movement of the workpiece during rolling of the tooth flank on the grinding disk so that an involute is ground. Said cam is secured interchangeably on the workpiece spindle or a part coupled therewith, such as on the rolling cam sleeve. Such a device is manufactured and sold by Carl Hurth Maschinen- und Zahnradfabrik of Munich, Germany, under the designation of SRS 400 Shaving Cutter and Grinding Machine and is illustrated by its bulletin SRS 400 1.0/3.75/e.
Also a rolling drive on a gear grinding machine is known in which the tension of the roll band or bands comprising the rolling drive means is responsive to at least one side of the rolling cam during the back-and-forth movement of the rolling cam carriage and same is accomplished by a guide bar or the like and a copying device through which the flank of the workpiece tooth not properly conforming to the desired involute can be corrected (German Pat. No. 2,059,521).
A rolling drive of the above-discussed type is the basis of the invention, in which the workpiece tooth flank can be corrected with simple means.
The basic purpose of the invention is attained by a rolling drive in which the pivot axis of the rolling cam can be adjusted relative to the axis of the workpiece spindle in at least one direction which lies for example parallel to the direction of movement of the rolling cam carriage. The invention can be appreciably improved by causing the pivot axis of the rolling cam to be adjustable both in the direction of the rolling movement of the rolling cam carriage and also perpendicularly thereto. The coordinates so referred to are those which are aligned perpendicularly to the axis of the workpiece spindle. The device is advantageously equipped for this purpose by providing appropriate adjusting means between a sleeve for holding said spindle and mounting means embracing same. A suitable housing or sleeve rotatably supports said spindle and it is self-supported by U-shaped member embracing said housing. Adjustment means are provided between said housing and said U-shaped means for moving the sleeve as desired with respect to said U-shaped holding device.
The device of the invention will not accomplish all of the functions of a gear grinding machine with a copying device. However, it is substantially less expensive and the correction possibilities are sufficient for many cases. By adjusting the rolling cam relative to the axis of the workpiece spindle it is possible to correct within limits the pitch circle or the pressure angle. Since this changes the position but not the radius of the rolling cam, there remains a position of inexactness, which, depending in which coordinate the adjustment is taking place, lies either at the tooth addendum or the tooth dedendum. Of course, it is also possible to combine the two coordinate adjustments, as is shown in the following exemplary embodiment. Then the circle of the adjusted rolling cam conforms sufficiently to the desired theoretical pitch circle that the error is negligible. On the other hand, it is possible to correct inaccuracies to which for example the workpiece chucking device may be subjected, with the device according to the invention namely with simpler means than with a copying device.
Further advantages and characteristics of the invention will become apparent on reading the following description.